Field of the Invention
This invention relates to a stitchbonded nonwoven fabric and a process for producing it by multi-needle stitching a nonwoven fibrous layer with two thread systems. More particularly, the invention concerns such a fabric and process for making it wherein one of the thread systems is a bulkable thread, the other is a substantially inextensible thread, and the threads are arranged in repeating patterns to form a drapable, durable, soft nonwoven fabric that is strong in both the longitudinal and transverse directions.
Description of the Prior Art
Nonwoven fabrics have long been used in a variety of applications. Unbonded, (i.e., not bonded) nonwoven fabrics most often have been used in applications that require little strength and durability. Such unbonded fabrics generally lack surface stability and often come apart when washed or laundered. To strengthen such fabrics, support layers often have been combined with the unbonded fabric. Strength has also been improved by bonding the fabric with a resin binder or binder fibers incorporated in the fabric. In addition to strengthening the fabric, bonding improves fabric stability and durability. However, bonding also makes the fabric stiff and boardy. Multi-needle stitching (i.e., stitchbonding) of unbonded nonwoven fabrics has also been used to increase fabric strength mainly in the direction of the stitching.
Use of bonded and unbonded, bulked nonwoven fabrics in disposable swim wear, towels, wash cloths, training pants for infants, baby wipes, scouring pads, mattresses, cushions, sleeping bags and the like has been disclosed, for example, by Wideman, U.S. Pat. No. 4,606,964. Morman, U.S. Pat. No. 4,657,802, column 1, line 30, through Column 4, line 32, discloses a large number of elastic nonwoven webs for use as diaper components, filters, bandages, wearing apparel, and the like. Neither patent mentions stitchbonded fabrics.
Multi-needle stitching machines, such as "Arachne", "Liba", or "Mali" machines (including Malimo, Malipol and Maliwatt machines) have been used to insert stitches into a wide variety of fibrous substrates. Such machines and some of the fabrics produced therewith are disclosed by K. W. Bahlo, "New Fabrics Without Weaving", Papers of the American Association of Textile Technology, Inc., pages 51-54 (November, 1965). Other disclosures of the use of such machines appear for example, in Ploch et al, U.S. Pat. No. 3,769,815, Hughes, U.S. Pat. No. 3,649,428 and Product Licensing Index, Research Disclosure, "Stitchbonded products of continuous filament nonwoven webs", page 30 (June, 1968). Warsop, U.S. Pat. No. 4,306,429, discloses a novel stitchbonded fleece made with incompletely threaded front and back bars of a multi-needle stitching machine. Hughes, U.S. Pat. Nos. 3,329,552 and 3,649,428, disclose other stitchbonded fabrics made with two thread systems. However, none of these disclosures concern stitching of a nonwoven fibrous layer with bulkable thread.
Multi-needle stitching of nonwoven fibrous layers with elastic thread (a type of bulkable thread) on one-bar stitchbonding machines is disclosed by Zafiroglu, U.S. Pat. No. 4,773,238, to make dust cloths.
Although each of the aforementioned nonwoven fabrics have been used with some success, their utility could be significantly enhanced by improvements in their combination of strength, softness, washability and durability properties. An object of this invention is to provide such an improvement.